1. Field of the Invention
The present invention relates to a light source device and a light beam scanning optical apparatus, and in particular, to a light source device and a light beam scanning optical apparatus to be used as image writing means of a laser printer or a digital copying machine.
2. Description of Related Arts
Conventionally, a variety of light beam scanning optical apparatuses have been known as means for writing an image onto a photosensitive member. In those apparatuses, a light beam emitted from a light source unit is scanned as deflected by a polygon mirror and focused on a photosensitive member via an f.theta.-lens or the like. A variety of optical members are housed in a box-shaped housing 100 opened upward as shown in FIG. 15. For example, the light source unit and the polygon mirror are housed in a recess portion 101 and a recess portion 102 of the housing 100, respectively, and after completing various adjustment works, the housing 100 is enclosed by a lid member (not shown).
In recent years, there has been growing demands for increasing a pixel density and increasing an image writing velocity. In compliance with these demands, there has been developed a multi-beam type optical apparatus in which two light sources are provided and light beams emitted from the respective light sources are scanned as deflected in a state in which they are close to each other in a sub-scanning direction so as to write two lines during one scan.
In the multi-beam system, two light sources are housed in the aforementioned recess portion 101, where members for retaining the light sources (laser diodes) are required to be adjusted in position from the directions of arrows h, and he for positional adjustment of the light beams. However, the side walls of the housing 100 become an obstacle in this adjustment, and therefore, it has been required to form an opening in either one of the directions of arrows h.sub.1 and h.sub.2 and execute the adjustment by inserting an adjusting instrument such as a screwdriver through this opening. As described above, it has been hard and troublesome to execute the positional adjustment sideways after the light source unit has been assembled into the housing 100.